Valve timing control apparatus

ABSTRACT

A valve timing control apparatus includes a driving-side rotation member, a driven-side rotation member, and a lock mechanism including a recess portion, a lock member engageable and disengageable relative to the recess portion, and a biasing member. The recess portion includes a lock groove portion with which the lock member is configured to engage to lock a relative rotation phase at a lock phase, and a restriction groove portion. The lock groove portion includes a lock bottom surface and the restriction groove portion includes a restriction bottom surface. A second depth from an opening position of the recess portion to the restriction bottom surface is smaller than a first depth from the opening position to the lock bottom surface. The second depth from the opening position to the restriction bottom surface is smaller than a third depth from the restriction bottom surface to the lock bottom surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 toJapanese Patent Application 2013-048412, filed on Mar. 11, 2013, theentire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to a valve timing control apparatus.

BACKGROUND DISCUSSION

A known valve timing control apparatus including a lock mechanismlocking a relative rotation phase between a driving-side rotation memberand a driven-side rotation member is disclosed, for example, inJP2004-257313A, which will be hereinafter referred to as Reference 1. Inthe valve timing control apparatus disclosed in Reference 1, adriven-side rotation member is provided at a radially inner side of adriving-side rotation member in a state where a relative rotation phasebetween the driven-side rotation member and the driving-side rotationmember is changeable. In addition, a rotation phase lock mechanism (lockmechanism) is provided to lock or secure the relative rotation phasebetween the driving-side rotation member and the driven-side rotationmember at a lock phase.

The valve timing control apparatus disclosed in Reference 1 includesmovable bodies serving as lock members which are projectable andretractable relative to an inner peripheral surface side of thedriving-side rotation member. Two grooves serving as recess portionswith which respective projection ends of the lock members engage areformed at portions at an outer periphery of the driven-side rotationmember so as to constitute a lock mechanism. The relative rotation phasebetween the driving-side rotation member and the driven-side rotationmember is locked in a state where the lock members engage with thecorresponding recess portions, which leads to a locked state of therelative rotation phase.

Each of the two recess portions in Reference 1 includes a steppedportion that includes a shallower depth than a depth of the entirerecess portion. In a state where the lock member engages with thestepped portion, the relative rotation phase between the driving-siderotation member and the driven-side rotation member is inhibited frombeing locked, i.e., the relative rotation phase is brought to arestricted state in which an available range of the relative rotationbetween the driving-side rotation member and the driven-side rotationmember is reduced. Specifically, in a case where the relative rotationphase is shifted to an advanced angle side, the lock member for anadvanced angle lock portion engages with the stepped portion of thecorresponding recess portion. In a case where the relative rotationphase is further shifted to the advanced angle side in theaforementioned engagement state between the lock member and the steppedportion, the lock member for a retarded angle lock portion engages withthe stepped portion of the corresponding recess portion. Thereafter, ina case where the relative rotation phase is further shifted to theadvanced angle side, the two lock members simultaneously engage with therespective two entire recess portions so that the relative rotationphase is brought to the locked state.

In the valve timing control apparatus disclosed in Reference 1, thedepth of the stepped portion to the bottom thereof from the outerperipheral surface of the driven-side rotation member is specified to besubstantially a half of the depth of the entire recess portion to thebottom thereof from the outer peripheral surface of the driven-siderotation member.

The lock mechanism of the valve timing control apparatus is provided fordetermining the valve opening and closing timing so as to smoothly startan internal combustion engine. In a case where an operation for stoppingthe engine, for example, an operation of an ignition key, is performed,the relative rotation phase of the valve timing control apparatus isshifted to the lock phase so that the engine is stopped after the lockedstate of the relative rotation is obtained.

In addition, the driven-side rotation member of the valve timing controlapparatus is connected to a camshaft of the internal combustion engine.Thus, because of a reaction force from the camshaft, the relativerotation phase changes (vibrates) alternately by a small amount in anadvanced angle direction and a retarded angle direction. Therefore, inthe valve timing control apparatus disclosed in Reference 1, in a casewhere the relative rotation phase is shifted in a direction of the lockphase so as to lock or secure the relative rotation phase at the lockphase, the lock member engages with the stepped portion before the lockmember engages with the entire recess portion. As a result, the changeof the relative rotation phase is reduced to achieve secure and promptshifting to the lock phase.

Nevertheless, even in a state where the lock member engages with thestepped portion, a possible weak engagement between the lock member andthe stepped portion may cause the lock member to disengage from thestepped portion, which may result in wasting time for the shifting ofthe relative rotation phase to the locked state.

A need thus exists for a valve timing control apparatus which is notsusceptible to the drawback mentioned above.

SUMMARY

According to an aspect of this disclosure, a valve timing controlapparatus includes a driving-side rotation member receiving a rotationpower from a crankshaft of an internal combustion engine, a driven-siderotation member arranged at a radially inner side of the driving-siderotation member and forming a void including an advanced angle chamberand a retarded angle chamber relative to an inner side surface of thedriving-side rotation member, the driven-side rotation member arrangedcoaxially with the driving-side rotation member and rotating integrallywith a camshaft for opening and closing a valve of the internalcombustion engine, and a lock mechanism including a recess portionformed at one of the driving-side rotation member and the driven-siderotation member, a lock member provided at the other of the driving-siderotation member and the driven-side rotation member to be engageable anddisengageable relative to the recess portion, and a biasing memberbiasing the lock member in a direction in which the lock member engageswith the recess portion. The recess portion includes a lock grooveportion with which the lock member is configured to engage to lock arelative rotation phase between the driving-side rotation member and thedriven-side rotation member at a lock phase, and a restriction grooveportion formed at a position connected to the lock groove portion toallow the relative rotation phase to change in a direction approachingthe lock phase and to prohibit the relative rotation phase to change ina direction away from the lock phase. The lock groove portion includes alock bottom surface with which a projecting end portion of the lockmember is configured to make contact. The restriction groove portionincludes a restriction bottom surface with which the projecting endportion of the lock member is configured to make contact. A second depthfrom an opening position of the recess portion to the restriction bottomsurface is smaller than a first depth from the opening position to thelock bottom surface. The second depth from the opening position to therestriction bottom surface is smaller than a third depth from therestriction bottom surface to the lock bottom surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of thisdisclosure will become more apparent from the following detaileddescription considered with the reference to the accompanying drawings,wherein:

FIG. 1 is a longitudinal section view of a valve timing controlapparatus according to an embodiment disclosed here;

FIG. 2 is a cross-sectional view of the valve timing control apparatustaken along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view of the valve timing control apparatusin which each lock member is in a lock released state;

FIG. 4 is a cross-sectional view of the valve timing control apparatusin a most retarded angle lock phase;

FIG. 5 is an explanatory diagram explaining a dimensional relationshipof a first lock recess portion;

FIG. 6 is an enlarged cross-sectional view illustrating a state in whichthe lock member engages with a restriction groove portion;

FIG. 7 is an enlarged cross-sectional view illustrating a locked stateof a relative rotation phase at an intermediate lock phase;

FIG. 8 is a cross-sectional view of the valve timing control apparatusaccording to a first modified embodiment disclosed here;

FIG. 9 is a cross-sectional view illustrating a state in which the lockmember engages with the restriction groove portion according to thefirst modified embodiment;

FIG. 10 is an enlarged cross-sectional view illustrating a state inwhich the lock member engages with a lock groove portion according tothe first modified embodiment;

FIG. 11 is an explanatory diagram explaining a dimensional relationshipof the first lock recess portion according to a second modifiedembodiment disclosed here;

FIG. 12 is an enlarged cross-sectional view illustrating the lockedstate of the relative rotation phase at the intermediate lock phaseaccording to the second modified embodiment; and

FIG. 13 is an enlarged cross-sectional view illustrating the lockedstate of the relative rotation phase at the intermediate lock phaseaccording to a third modified embodiment disclosed here.

DETAILED DESCRIPTION

An embodiment will be explained with reference to the attached drawings.As illustrated in FIGS. 1 and 2, a valve timing control apparatus of theembodiment controls an opening and closing timing of an intake valve 2by changing a relative rotation phase between an outer rotor 10 servingas a driving-side rotation member and an inner rotor 20 serving as adriven-side rotation member (which will be hereinafter simply referredto as a relative rotation phase). The outer rotor 10 rotates insynchronization with a crankshaft 1 of an engine E serving as aninternal combustion engine. The inner rotor 20 is connected to acamshaft 3 for opening and closing the intake valve 2 of the engine E.The outer rotor 10 and the inner rotor 20 are coaxially arranged witheach other.

The engine E is provided at a vehicle, for example, a passenger car. Thevalve timing control apparatus is controlled by an engine control unit 5serving as an electronic control unit (ECU). The engine control unit 5,which will be hereinafter referred to as the ECU 5, acquires feedbackinformation from the engine E or driver's operation information, forexample, and operates an electromagnetic phase control valve 31 and anelectromagnetic lock control valve 32. The phase control valve 31 andthe lock control valve 32 are accommodated within a single valve unit V.A portion of the valve unit V is inserted to be positioned within thevalve timing control apparatus.

As illustrated in FIGS. 1 to 4, the valve timing control apparatusincludes the outer rotor 10 rotating in synchronization with thecrankshaft 1 of the engine E and the inner rotor 20 connected via aconnection bolt 23 to the camshaft 3 that opens and closes the intakevalve 2 provided at a combustion chamber of the engine E. The outerrotor 10 and the inner rotor 20 are coaxially arranged with a rotationaxis X of the camshaft 3. The outer rotor 10 and the inner rotor 20 arerelatively rotatable around the rotation axis X.

The outer rotor 10 includes a rotor body 11 in a cylindrical form, arear block 12, and a front plate 13 all of which are tightened to oneanother by plural fastening bolts 14. The rear block 12 is arranged incontact with a first end portion of the rotor body 11 along the rotationaxis X. The front plate 13 is arranged in contact with a second endportion of the rotor body 11 along the rotation axis X. The rear block12 is positioned to close an opening of the outer rotor 10 at a firstside while the front plate 13 is positioned to close an opening of theouter rotor 10 at a second side. A sprocket 12S is formed at an outerperiphery of the rear block 12 so as to serves as a passive portion towhich a rotation power is transmitted from the crankshaft 1. The rotorbody 11 includes an inner wall surface in a cylindrical form (i.e., acylindrical inner wall surface) and plural projecting portions 11Tprojecting in a direction to approach the rotation axis X, i.e., to aradially inner side, the cylindrical inner wall surface and theprojecting portions 11T being integrally formed each other.

A pair of guide grooves is formed at the projecting portion 11T radiallyfrom the rotation axis X. Lock members 15 each in a plate form areinserted to the respective guide grooves so as to be projectable andretractable, i.e., slidable. Lock springs 16 each serving as a biasingmember are provided at an inner portion of the rotor body 11 to bias therespective lock members 15 to come close to the rotation axis X. One ofthe lock members 15 and the lock spring 16 that biases theaforementioned lock member 15 in a projecting direction thereofconstitute a first lock mechanism L1. The other of the lock members 15and the lock spring 16 that biases the aforementioned lock member 15 ina projecting direction thereof constitute a second lock mechanism L2.Each of the lock members 15 is not limited to include a plate form andmay include a rod form, for example.

The inner rotor 20 includes an inner peripheral surface 20S in acylindrical form coaxial with the rotation axis X and an outerperipheral surface 20T relative to (coaxial with) the rotation axis X.Plural vanes 21 projecting radially outwardly are fitted into the outerperipheral surface 20T. As illustrated in FIG. 1, a flange portion 22 isformed at one end portion of the inner rotor 20 along the rotation axisX. The inner rotor 20 is connected to the camshaft 3 by the connectionbolt 23 that is inserted to be positioned within a bore coaxial with therotation shaft X and formed at a radially inner side of the flangeportion 22. As illustrated in FIGS. 2 to 4, advanced angle flow passages24 connected to respective advanced angle chambers Ca, retarded angleflow passages 25 connected to respective retarded angle chambers Cb, anda pair of lock release flow passages 26 are formed at the inner rotor20. The inner rotor 20 forms voids relative to an inner side surface ofthe outer rotor 10, each of the voids including the advanced anglechamber Ca and the retarded angle chamber Cb.

An outer diameter of the outer peripheral surface 20T of the inner rotor20 is specified to be a value so that the outer peripheral surface 20Tof the inner rotor 20 is fitted to projecting ends of the respectiveprojecting portions 11T of the rotor body 11 of the outer rotor 10 in atightly contacting manner. In addition, a projection length of each ofthe vanes 21 is specified so that a projecting end of each of the vanes21 is in contact with the cylindrical inner wall surface of the rotorbody 11. Accordingly, the inner rotor 20 is fitted to the outer rotor 10to form fluid chambers C at an area surrounded by an inner side surfaceof the rotor body 11, i.e., the cylindrical inner wall surface and theplural projecting portions 11T, and the outer peripheral surface 20T ofthe inner rotor 20. Further, the vane 21 divides each of the fluidchambers C into the advanced angle chamber Ca and the retarded anglechamber Cb.

A first lock recess portion 27 serving as a recess portion relative towhich the lock member 15 of the first lock mechanism L1 is engageableand disengageable, and a second lock recess portion 28 relative to whichthe lock member 15 of the second lock mechanism L2 is engageable anddisengageable are formed at an outer periphery of the inner rotor 20.Specifically, the first lock recess portion 27, the second lock recessportion 28, and a most retarded angle lock recess portion 29 serve asrecess portions formed at the outer peripheral surface 20T of the innerrotor 20 to be recessed towards the rotation axis X as illustrated inFIGS. 2 to 5. One of the lock release flow passages 26 is connected tothe first lock recess portion 27 while the other of the lock releaseflow passages 26 is connected to the second lock recess portion 28. Oneof the advanced angle flow passages 24 connected to the advanced anglechamber Ca is formed in the vicinity of the first lock recess portion27. The most retarded angle lock recess portion 29 is formed at anopening portion of the aforementioned advanced angle flow passage 24positioned in the vicinity of the first lock recess portion 27. Aconnection flow passage 24A is formed in a groove at the outer peripheryof the inner rotor 20 for allowing hydraulic oil to flow between theadvanced angle flow passage 24 and the advanced angle chamber Caadjacent to the advanced angle flow passage 24.

As illustrated in FIG. 2, the lock member 15 of the first lock mechanismL1 is fitted to the first lock recess portion 27 and at the same timethe lock member 15 of the second lock mechanism L2 is fitted to thesecond lock recess portion 28 to thereby obtain an intermediate lockphase serving as a lock phase. In addition, as illustrated in FIG. 4,the lock member 15 of the second lock mechanism L2 is fitted to the mostretarded angle lock recess portion 29 to thereby obtain a most retardedangle lock phase.

The valve timing control apparatus is configured in a state where theinner rotor 20 is fitted to the inner side of the rotor body 11 of theouter rotor 10, and the rear block 12 and the front plate 13 arearranged at positions to sandwich and dispose the rotor body 11 and theinner rotor 20. The rotor body 11, the rear block 12, and the frontplate 13 are connected to one another by the fastening bolts 14. Theplural vanes 21 and the two lock members 15 are arranged to contact withan inner side surface of the rear block 12 and an inner side surface ofthe front plate 13.

A torsion spring 17 is arranged between the rear block 12 of the outerrotor 10 and the inner rotor 20. The torsion spring 17 applies a biasingforce until the relative rotation phase at least reaches theintermediate lock phase from a state in which the relative rotationphase is at the most retarded angle, for example.

As mentioned above, in the valve timing control apparatus, the innerrotor 20 is positioned at the radially inner side of the outer rotor 10to thereby form the fluid chambers C. Each of the fluid chambers C isdivided by the vane 21 to the advanced angle chamber Ca and the retardedangle chamber Cb. The advanced angle flow passage 24 is connected to theadvanced angle chamber Ca while the retarded angle flow passage 25 isconnected to the retarded angle chamber Cb. The lock members 15 of thefirst lock mechanism L1 and the second lock mechanism L2 are configuredto be arranged at positions at which the lock members 15 are fitted tothe first lock recess portion 27 and the second lock recess portion 28,respectively.

In the valve timing control apparatus, a timing chain 4 is arranged andwound between an output sprocket 1S provided at the crankshaft 1 of theengine E and the sprocket 12S of the outer rotor 10. Accordingly, theouter rotor 10 rotates in synchronization with the crankshaft 1. In theembodiment, the sprocket 12S is formed at the outer rotor 10.Alternatively, a timing pulley may be formed at the outer rotor 10.Then, the rotation power of the crankshaft 1 may be transmitted to thetiming pulley via a timing belt. Further alternatively, a gear portionmay be formed at an outer surface of the outer rotor 10. Then, therotation power of the crankshaft 1 may be transmitted to the gearportion via a gear train. The valve timing control apparatus of theembodiment is not limited to control the opening and closing timing ofthe intake valve 2 and may control the opening and closing timing of anexhaust valve of the engine E. Alternatively, the valve timing controlapparatus of the embodiment may control the opening and closing timingof both the intake valve 2 and the exhaust valve.

In the valve unit V, the phase control valve 31 and the lock controlvalve 32 are accommodated in a unit case. A flow passage forming shaftportion 33 that is integrally formed at the unit case is inserted to theinner peripheral surface 20S of the inner rotor 20. A groove portion inan annular form connected to a port of the phase control valve 31 and agroove portion in an annular form connected to a port of the lockcontrol valve 32 are formed at an outer periphery of the flow passageforming shaft portion 33. Then, plural seals 34 each in a ring form areprovided between the outer periphery of the flow passage forming shaftportion 33 and the inner peripheral surface 20S of the inner rotor 20 soas to separate the aforementioned groove portions from each other.

The engine E includes a hydraulic pump P driven to supply oil stored inan oil pan as hydraulic oil. A flow passage is formed to supply thehydraulic oil from the hydraulic pump P to the phase control valve 31and the lock control valve 32.

As illustrated in FIG. 5, the first lock recess portion 27 includes alock groove portion Ta, and a restriction groove portion Tb (steppedportion) at a position connected to an opening of the lock grooveportion Ta so as to be formed in a stepped manner by including ashallower depth than a depth of the lock groove portion Ta. In a statewhere the relative rotation phase is at the intermediate lock phase, thelock member 15 of the first lock mechanism L1 engages with the lockgroove portion Ta so as to fix or lock the relative rotation phase atthe intermediate lock phase (lock phase). The restriction groove portionTb is configured to engage with the lock member 15 to thereby allow therelative rotation phase to be shifted in a direction approaching theintermediate lock phase from a retarded angle phase and restrict therelative rotation phase to be shifted in a direction away from theintermediate lock phase. At this time, a positional relation between therestriction groove portion Tb and the lock groove portion Ta may bespecified so that the restriction groove portion Tb allows the relativerotation phase to be shifted in a direction approaching the intermediatelock phase from an advanced angle phase.

In a state where the lock member 15 of the first lock mechanism L1engages with the lock groove portion Ta of the first lock recess portion27, the lock member 15 of the second lock mechanism L2 engages with thesecond lock recess portion 28 as illustrated in FIG. 2.

The lock groove portion Ta includes a lock bottom surface Ua with whicha projecting end portion 115 of the lock member 15 is contactable. Inaddition, the lock groove portion Ta includes a main vertical wallsurface Wa with which the lock member 15 is contactable, and a subvertical wall surface Wb with which the lock member 15 makes contact inthe intermediate lock phase. Specifically, in the lock groove portionTa, the main vertical wall surface Wa is formed at a wall portion in araised manner relative to the lock bottom surface Ua at a positionfacing the advanced angle side, i.e., a position adjacent to therestriction groove portion Tb. The sub vertical wall surface Wb isformed at a wall portion in a raised manner relative to the lock bottomsurface Ua at a position opposite from the aforementioned positionadjacent to the restriction groove portion Tb. The main vertical wallsurface Wa and the sub vertical wall surface Wb are formed to extendalong the depth direction of the first lock recess portion 27. The mainvertical wall surface Wa is formed at a portion of an area along thedepth direction from an end portion of the lock groove portion Ta at aside of the opening position of the first lock recess portion 27.

The restriction groove portion Tb includes a restriction bottom surfaceUb with which the projecting end portion 115 of the lock member 15 iscontactable. The restriction groove portion Tb includes a restrictionwall Wr formed in a raised manner relative to the restriction bottomsurface Ub at a position facing the advanced angle side.

In the embodiment, a projection is formed at the lock bottom surface Uafor easily supplying the hydraulic oil to the projecting end portion 115of the lock member 15 in a case where the locked state of the relativerotation is released in a state where the lock member 15 engages withthe lock bottom surface Ua. In the following explanation, a projectionend of the projection is defined as the position of the lock bottomsurface Ua. Without forming the projection, a groove may be formed atthe lock bottom surface Ua so that the hydraulic oil is supplied to theprojecting end portion 115 of the lock member 15 in engagement with thelock bottom surface Ua. In such case, a flat portion of the lock bottomsurface Ua serves as the position of the lock bottom surface Ua.

Specifically, a depth (i.e., a distance in a depth direction) from theouter peripheral surface 20T of the inner rotor 20 corresponding to anopening position of the lock groove portion Ta (the first lock recessportion 27) to the lock bottom surface Ua of the first lock recessportion 27 is specified to be a predetermined depth (distance), whichwill be hereinafter referred to as a first depth D1 serving as a firstdepth. A depth from the outer peripheral surface 20T of the inner rotor20 corresponding to the opening position of the lock groove portion Ta(the first lock recess portion 27) to the restriction bottom surface Ubof the first lock recess portion 27, which will be hereinafter referredto as a restriction depth Db serving as a second depth, is specified tobe smaller than a depth from the restriction bottom surface Ub to thelock bottom surface Ua, which will be hereinafter referred to as a lockdepth Da serving as a third depth. According to the aforementioned depthrelationship, the restriction depth Db is smaller than a half of thefirst depth D1.

A depth from the outer peripheral surface 20T of the inner rotor 20 to asecond bottom surface 28U of the second lock recess portion 28, and adepth from the outer peripheral surface 20T of the inner rotor 20 to athird bottom surface 29U of the most retarded angle lock recess portion29 are specified to be the same. In addition, one of a pair of verticalwall surfaces formed at the second lock recess portion 28 at theadvanced angle side forms an advanced angle side vertical wall surfaceVa with which the lock member 15 makes contact in the intermediate lockphase. The other of the pair of vertical wall surfaces formed at thesecond lock recess portion 28 at the retarded angle side forms aretarded angle side vertical wall surface Vb with which the lock member15 is contactable.

A depth of the main vertical wall surface Wa, a depth of the restrictionwall Wr, a depth of the sub vertical wall surface Wb of the first lockrecess portion 27, a depth of the advanced angle side vertical wallsurface Va and a depth of the retarded angle side vertical wall surfacesVb of the second lock recess portion 28 are specified to be the same.That is, portions of a pair of wall surfaces of the first lock recessportion 27 connected to the lock bottom surface Ua are partially cut andremoved, for example, to form the main vertical wall surface Wa and thesub vertical wall surface Wb. In the same way, the advanced angle sidevertical wall surface Va and the retarded angle side vertical wallsurface Vb are formed.

As illustrated in FIGS. 1 and 2, in the valve timing control apparatus,the outer rotor 10 rotates in a driving rotation direction S by adriving force transmitted from the crankshaft 1 via the timing chain 4.The direction same as the driving rotation direction S in which theinner rotor 20 rotates relative to the outer rotor 10 is referred to asan advanced angle direction Sa. The direction opposite from the advancedangle direction Sa is referred to as a retarded angle direction Sb. Inthe valve timing control apparatus, a relationship between thecrankshaft 1 and the camshaft 3 is specified so that an intake aircompression ratio increases in association with an increase of adisplacement amount of the relative rotation phase in the advanced angledirection Sa, and the intake air compression ratio decreases inassociation with the increase of the displacement amount of the relativerotation phase in the retarded angle direction Sb.

Each of the fluid chambers C is divided by the vane 21 into the advancedangle chamber Ca to which the hydraulic fluid is supplied to displacethe relative rotation phase in the advanced angle direction Sa, and theretarded angle chamber Cb to which the hydraulic fluid is supplied todisplace the relative rotation phase in the retarded angle direction Sb.The relative rotation phase in a state where the vane 21 reaches amoving end (i.e., a rotation limit relative to the rotation axis X) inthe advanced angle direction Sa is referred to as the most advancedangle phase. The relative rotation phase in a state where the vane 21reaches a moving end (i.e., the rotation limit relative to the rotationaxis X) in the retarded angle direction Sb is referred to as the mostretarded angle phase.

The most retarded angle phase includes not only the moving end in theretarded angle direction Sb but also the vicinity of the moving end inthe retarded angle direction Sb. In the same way, the most advancedangle phase includes not only the moving end in the advanced angledirection Sa but also the vicinity of the moving end in the advanceddirection Sa.

In the valve timing control apparatus, as illustrated in FIGS. 2 and 7,the lock member 15 of the first lock mechanism L1 engages with the lockgroove portion Ta of the first lock recess portion 27 by the biasingforce of the lock spring 16 and at the same time the lock member 15 ofthe second lock mechanism L2 engages with the second lock recess portion28 by the biasing force of the lock spring 16 so as to restrict and stopthe relative rotation between the outer rotor 10 and the inner rotor 20.Such rotation phase is the intermediate lock phase in which optimalintake air timing is obtained for the start of the engine E in a statewhere the engine E radiates heat.

In addition, as illustrated in FIG. 4, in a state where the lock member15 of the second lock mechanism L2 engages with the most retarded anglelock recess portion 29 by the biasing force of the lock spring 16, therelative rotation between the outer rotor 10 and the inner rotor 20 isrestricted. The thus obtained relative rotation phase is the mostretarded angle lock phase serving as the relative rotation phase closerto the most retarded angle. In the most retarded angle lock phase,optimal intake air timing is specified for the start of the engine E ina state where the engine E is inhibited from radiating heat, forexample, when the engine E is restarted in the idling stop state.

In a case where the relative rotation phase is changed from the mostretarded angle lock phase to the intermediate lock phase, the phasecontrol valve 31 is operated to supply the hydraulic oil to the advancedangle flow passage 24 so that the engagement of the lock member 15 withthe most retarded angle lock recess portion 29 is released and therelative rotation phase is shifted in the advanced angle direction Sa.The shifting of the relative rotation phase in the advanced angledirection Sa proceeds so that the lock member 15 of the first lockmechanism L1 first engages with the restriction groove portion Tb of thefirst lock recess portion 27 by the biasing force of the lock spring 16as illustrated in FIG. 6.

In a case where the relative rotation phase is shifted in the advancedangle direction Sa, a reaction force from the camshaft 3 is applied tothe inner rotor 20. Thus, the relative rotation phase changes (vibrates)by a small amount alternately in the advanced angle direction Sa and theretarded angle direction Sb.

As mentioned above, the restriction depth Db is specified to be smallerthan a half of the first depth D1 of the first lock recess portion 27.Thus, as compared to a case where the restriction depth Db is specifiedto be a half of the first depth D1, for example, a time period may bereduced for the projecting end portion 115 of the lock member 15 of thefirst lock mechanism L1 to move to a boundary position (i.e., anedge-shaped portion) between the restriction bottom surface Ub and thelock groove portion Ta from the restriction groove portion Tb after theprojecting end portion 115 of the lock member 15 enters the restrictiongroove portion Tb in a case where the relative rotation phase is shiftedin the advanced angle direction Sa. The lock member 15 may be promptlybrought to a state engaging with the lock groove portion Ta. Inaddition, in a state where the projecting end portion 115 of the lockmember 15 engages with the restriction groove portion Tb, the strongbiasing force of the lock spring 16 is maintained, thereby maintainingthe strong engagement state of the lock member 15 with the restrictiongroove portion Tb.

In a case where the reaction force from the camshaft 3 is applied to theinner rotor 20 in the retarded angle direction Sb in a state where theprojecting end portion 115 of the lock member 15 engages with therestriction groove portion Tb, the lock member 15 strongly makes contactwith the restriction wall Wr. Even in the aforementioned strong contactstate, the lock member 15 is maintained in engagement with therestriction groove portion Tb by the strong biasing force of the lockspring 16. As a result, the lock member 15 is inhibited from disengagingfrom the restriction groove portion Tb.

Then, the relative rotation phase is shifted in the advanced angledirection Sa so that the lock member 15 of the second lock mechanism L2is brought to a state engaging with the second lock recess portion 28.Afterwards, the lock member 15 of the first lock mechanism L1 is broughtto a state engaging with the lock groove portion Ta. Consequently, asillustrated in FIG. 7, the relative rotation phase is locked at theintermediate lock phase. In the aforementioned configuration, the lockdepth Da is specified to be greater than the restriction depth Db. Thus,even in a case where dirt or dust enters the lock bottom surface Ua, forexample, the engagement of the lock member 15 relative to the lockgroove portion Ta may be secured.

In a state where the relative rotation phase reaches the intermediatelock phase, the lock member 15 of the first lock mechanism L1 ispositioned close to the sub vertical wall surface Wb of the first lockrecess portion 27 with a predetermined clearance. The lock member 15 ofthe second lock mechanism L2 is positioned close to the advanced angleside vertical wall surface Va of the second lock recess portion 28 witha predetermined clearance. Consequently, the relative rotation phase issecurely locked at the intermediate lock phase.

The engine E is stopped in a state where the relative rotation phase isat the intermediate lock phase. At the start of the engine E that isstopped, the locked state of the relative rotation phase at theintermediate lock phase is released to thereby change the relativerotation phase. In the case of releasing the locked state of therelative rotation phase, the hydraulic oil is supplied to the lockrelease flow passage 26 by the operation of the lock control valve 32.

Because an area at which the lock member 15 of the first lock mechanismL1 is in contact with the sub vertical wall surface Wb of the first lockrecess portion 27 is small and an area at which the lock member 15 is incontact with the advanced angle side vertical wall surface Va of thesecond lock recess portion 28 is small, a small friction force isapplied to each of the lock members 15 of the first and second lockmechanisms L1 and L2 when the locked state of the relative rotationphase is released. Thus, a smooth release of the locked state of therelative rotation phase is achievable.

The aforementioned embodiment may be modified or changed as follows. Themodified embodiments bear the same reference numerals as theaforementioned embodiment for members including the similar functions.

As illustrated in FIGS. 8 to 10, according to a first modifiedembodiment, the plural vanes (vane portions) 21 are integrally formed atthe inner rotor 20 so that the fluid chamber C is divided into theadvanced angle chamber Ca and the retarded angle chamber Cb by each ofthe vanes 21. A lock mechanism L includes the lock member 15 provided atone of the vanes 21, the lock member 15 moving along the rotation axisX.

In the modified embodiment, the lock member 15 is formed in a column.The lock member 15 is accommodated in a bore portion 21A formed at thevane 21 so as to be slidably movable in the direction along the rotationaxis X. The lock member 15 is biased by the lock spring 16 in adirection to project. In addition, the lock member 15 includes a largediameter portion 15A at a first end and a small diameter portion 15B ata second end to thereby form a stepped portion at an intermediateportion. A void is formed at the large diameter portion 15A toaccommodate a portion of the lock spring 16.

A penetration bore is formed at the vane 21 so that the small diameterportion 15B of the lock member 15 is inserted to be positioned withinthe penetration bore. In addition, the lock release flow passage 26 isformed at the vane 21 for operating the lock member 15 in a lock releasedirection by the supply of the hydraulic oil to the stepped portion ofthe lock member 15. The first lock recess portion 27 is formed at therear block 12 so that the projecting end portion 115 of the smalldiameter portion 15B of the lock member 15 is engageable anddisengageable relative to the first lock recess portion 27. At thistime, alternatively, a recess portion relative to which the lock member15 is engageable and disengageable may be formed at the front plate 13.

In the first modified embodiment, in the same way as the aforementionedembodiment, the first lock recess portion 27 includes the lock grooveportion Ta and the restriction groove portion Tb that is formed at aposition connected to the opening of the lock groove portion Ta so as tobe formed in a stepped manner by including a shallower depth than adepth of the lock groove portion Ta. The lock groove portion Tafunctions so that the relative rotation phase is locked at theintermediate lock phase (lock phase) by the engagement with the lockmember 15 in a state where the relative rotation phase is at theintermediate lock phase. The restriction groove portion Tb functions soas to allow the relative rotation phase to change in a directionapproaching the intermediate lock phase and to prohibit the relativerotation phase to change in a direction away from the intermediate lockphase.

The lock groove portion Ta includes the lock bottom surface Ua withwhich the projecting end portion 115 of the lock member 15 iscontactable. The restriction groove portion Tb includes the restrictionbottom surface Ub with which the projecting end portion 115 of the lockmember 15 is contactable. The depth from the opening position to thelock bottom surface Ua of the first lock recess portion 27 is specifiedto be a predetermined depth (depth value), i.e., the first depth D1. Thedepth from the opening position to the restriction bottom surface Ub ofthe first lock recess portion 27, i.e., the restriction depth Db, isspecified to be smaller than the depth from the restriction bottomsurface Ub to the lock bottom surface Ua, i.e., the lock depth Da.According to the aforementioned depth relationship, the restrictiondepth Db is smaller than a half of the first depth D1.

In the first modified embodiment, as compared to a case where therestriction depth Db is specified to be a half of the first depth D1,for example, a time period may be reduced for the projecting end portion115 of the lock member 15 to move to a boundary position (i.e., anedge-shaped portion) between the restriction bottom surface Ub and thelock groove portion Ta from the restriction groove portion Tb after theprojecting end portion 115 of the lock member 15 enters the restrictiongroove portion Tb in a case where the relative rotation phase is shiftedin the advanced angle direction Sa because the restriction depth Db issmaller than the lock depth Da. The lock member 15 may be promptlybrought to a state engaging with the lock groove portion Ta. Inaddition, in a state where the projecting end portion 115 of the lockmember 15 engages with the restriction groove portion Tb, the strongbiasing force of the lock spring 16 is maintained, thereby maintainingthe strong engagement state of the lock member 15 with the restrictiongroove portion Tb. In a case where the relative rotation phase isshifted in the advanced angle direction Sa, the projecting end portion115 of the lock member 15 is securely guided and inserted to the lockgroove portion Ta to hold the intermediate lock phase.

As illustrated in FIGS. 11 and 12, according to a second modifiedembodiment, the first lock recess portion 27 includes the lock grooveportion Ta and the restriction groove portion Tb that is formed at aposition connected to the opening of the lock groove portion Ta so as tobe formed in a stepped manner by including a shallower depth than adepth of the lock groove portion Ta in the same way as theaforementioned embodiments. The lock groove portion Ta functions so thatthe relative rotation phase is locked at the intermediate lock phase(lock phase) by the engagement with the lock member 15 of the first lockmechanism L1 in a state where the relative rotation phase is at theintermediate lock phase. The restriction groove portion Tb functions soas to allow the relative rotation phase to change in a directionapproaching the intermediate lock phase from the retarded angle phaseand to prohibit the relative rotation phase to change in a directionaway from the intermediate lock phase.

In a state where the relative rotation phase reaches the intermediatelock phase, the lock member 15 of the first lock mechanism L1 ispositioned close to the main vertical wall surface Wa of the first lockrecess portion 27 with a predetermined clearance. The lock member 15 ofthe second lock mechanism L2 is positioned close to the retarded angleside vertical wall surface Vb of the second lock recess portion 28 witha predetermined clearance. Consequently, the relative rotation phase issecurely locked at the intermediate lock phase.

In the second modified embodiment in which the engagement state betweenthe lock members 15 and the first and second recess portions 27 and 28at the intermediate lock phase is differently specified, a time periodmay be reduced for the projecting end portion 115 of the lock member 15of the first lock mechanism L1 to move to a boundary position (i.e., anedge-shaped portion) between the restriction bottom surface Ub and thelock groove portion Ta from the restriction groove portion Tb after theprojecting end portion 115 of the lock member 15 enters the restrictiongroove portion Tb in a case where the relative rotation phase is shiftedin the advanced angle direction Sa from the retarded angle side. Thelock member 15 may be promptly brought to a state engaging with the lockgroove portion Ta. In addition, in a state where the projecting endportion 115 of the lock member 15 engages with the restriction grooveportion Tb, the strong biasing force of the lock spring 16 ismaintained, thereby maintaining the strong engagement state of the lockmember 15 with the restriction groove portion Tb.

As illustrated in FIG. 13, in a third modified embodiment, the secondlock recess portion 28 may include a lock groove portion Tc and arestriction groove portion Td including the same depths as the lockgroove portion Ta and the restriction groove portion Tb of the firstlock recess portion 27 as in the aforementioned embodiments. The lockmember 15 of the first lock mechanism L1 engages with the restrictiongroove portion Tb of the first lock recess portion 27 and thereafter thelock member 15 of the second lock mechanism L2 engages with therestriction groove portion Td of the second lock recess portion 28. Inthe aforementioned configuration, the lock member 15 at the second lockrecess portion 28 operates in the same way as the lock member 15 at thefirst lock recess portion 27.

Instead of the pair of lock members 15, a single lock member 15 may beprovided. Even in such configuration, the relative rotation phase may belocked at a desired phase.

The lock member 15 may be supported to be projectable and retractablerelative to the inner rotor 20 (driven-side rotation member) and arecess portion may be formed at the outer rotor 10 (driving-siderotation member). The projecting end portion 115 of the lock member 15is configured to be engageable and disengageable relative to the recessportion. According to the aforementioned configuration, the secureengagement of the lock member 15 with the recess portion may beachieved, the recess portion at which the lock groove portion Ta and therestriction groove portion Tb are formed adjacent to each other.

According to the aforementioned embodiments, the depth from the openingposition of the first lock recess portion 27 corresponding to the outerperipheral surface 20T of the inner rotor 20 to the restriction bottomsurface Ub, i.e., the restriction depth Db, is smaller than a half ofthe depth from the opening position of the first lock recess portion 27to the lock bottom surface Ua, i.e., the first depth D1. Thus, ascompared to a case where the restriction depth Db is specified to be ahalf of the first depth D1, for example, a time period may be reducedfor the projecting end portion 115 of the lock member 15 to move to aboundary position between the restriction bottom surface Ub and the lockgroove portion Ta from the restriction groove portion Tb after theprojecting end portion 115 of the lock member 15 enters the restrictiongroove portion Tb in a case where the relative rotation phase betweenthe outer rotor 10 (driving-side rotation member) and the inner rotor 20(driven-side rotation member) changes in a direction in which the lockmember 15 moves to engage with the lock groove portion Ta. The lockmember 15 may be promptly brought to a state engaging with the lockgroove portion Ta. In addition, in a case where an elastic deformation,for example, the lock spring 16, is used as the biasing member, thebiasing force applied to the lock member 15 from the lock spring 16 islarge in a state where the lock member 15 is in contact with therestriction bottom surface Ub, as compared to a case where therestriction depth Db is specified to be a half of the first depth D1.The lock member 15 may be maintained in contact with the restrictionbottom surface Ub by a strong force. Therefore, in a case where therelative rotation phase between the outer rotor 10 and the inner rotor20 is shifted in a direction of the intermediate lock phase, the strongengagement state in which the lock member 15 is in engagement with therestriction groove portion Tb is maintained. The relative rotation phasemay be also easily brought to the locked state. As a result, a state inwhich the lock member 15 engages with the restriction groove portion Tb(stepped portion) of the first lock recess portion 27 is securelymaintained to smoothly obtain the locked state of the relative rotationphase.

According to the aforementioned embodiments, the lock groove portion Taof the first lock recess portion 27 includes the main vertical wallsurface Wa and the sub vertical wall surface Wb formed to extend alongthe depth direction of the first lock recess portion 27, and the mainvertical wall surface Wa which is positioned adjacent to the restrictiongroove portion Tb and with which the lock member 15 is contactable isformed at a portion of an area along the depth direction from an endportion of the lock groove portion Ta at a side of the opening positionof the first lock recess portion 27.

Accordingly, a contact area between the lock member 15 and the wallportion of the lock groove portion Ta at which the main vertical wallsurface Wa is formed may be reduced in a state where the lock member 15engages with the lock groove portion Ta. As a result, a contactresistance between the lock member 15 and the wall portion in a casewhere the lock member 15 moves in the lock release direction is reducedto thereby easily release the locked state of the relative rotation.

The principles, preferred embodiment and mode of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiments disclosed. Further,the embodiments described herein are to be regarded as illustrativerather than restrictive. Variations and changes may be made by others,and equivalents employed, without departing from the spirit of thepresent invention. Accordingly, it is expressly intended that all suchvariations, changes and equivalents which fall within the spirit andscope of the present invention as defined in the claims, be embracedthereby.

1. A valve timing control apparatus comprising: a driving-side rotationmember receiving a rotation power from a crankshaft of an internalcombustion engine; a driven-side rotation member arranged at a radiallyinner side of the driving-side rotation member and forming a voidincluding an advanced angle chamber and a retarded angle chamberrelative to an inner side surface of the driving-side rotation member,the driven-side rotation member arranged coaxially with the driving-siderotation member and rotating integrally with a camshaft for opening andclosing a valve of the internal combustion engine; a lock mechanismincluding a recess portion formed at one of the driving-side rotationmember and the driven-side rotation member, a lock member provided atthe other of the driving-side rotation member and the driven-siderotation member to be engageable and disengageable relative to therecess portion, and a biasing member biasing the lock member in adirection in which the lock member engages with the recess portion; therecess portion including a lock groove portion with which the lockmember is configured to engage to lock a relative rotation phase betweenthe driving-side rotation member and the driven-side rotation member ata lock phase, and a restriction groove portion formed at a positionconnected to the lock groove portion to allow the relative rotationphase to change in a direction approaching the lock phase and toprohibit the relative rotation phase to change in a direction away fromthe lock phase, the lock groove portion including a lock bottom surfacewith which a projecting end portion of the lock member is configured tomake contact, the restriction groove portion including a restrictionbottom surface with which the projecting end portion of the lock memberis configured to make contact, a second depth from an opening positionof the recess portion to the restriction bottom surface being smallerthan a first depth from the opening position to the lock bottom surface,the second depth from the opening position to the restriction bottomsurface being smaller than a third depth from the restriction bottomsurface to the lock bottom surface.
 2. The valve timing controlapparatus according to claim 1, wherein the lock groove portion of therecess portion includes vertical wall surfaces formed to extend along adepth direction of the recess portion, and one of the vertical wallsurfaces which is positioned adjacent to the restriction groove portionand with which the lock member is contactable is formed at a portion ofan area along the depth direction from an end portion of the lock grooveportion at a side of the opening position of the recess portion.